United States President Donald Trump tweeted on Wednesday that Russia should be on standby as Washington prepares a response after the chemical attacks that hit Syria’s Douma earlier this week.

“Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and “smart!” You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!,” Trump tweeted on Wednesday.

Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and “smart!” You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!

Trump administration officials consulted with global allies Tuesday on a possible joint military response to Syria’s alleged poison gas attack, as President Donald Trump canceled a foreign trip in order to manage a crisis that is testing his vow to stand up to Syrian President Bashar Assad.

Trump spoke with other world leaders, and other US officials said the US, France and Britain were in extensive consultations about launching a military strike as early as the end of this week. None of the three countries’ leaders had made a firm decision, according to the officials, who were not authorized to discuss military planning by name.

Pentagon ‘ready’ to provide military options for Syria

Defense Secretary Jim Mattis said Wednesday the Pentagon is ready to provide options for a Syria strike in response to a suspected chemical attack, but noted the US and its allies are still gathering information.

"We are still assessing the intelligence, ourselves and our allies, we are still working on this," Mattis said when asked if he had seen enough evidence to blame President Bashar al-Assad's regime for the alleged chemical attack in Douma.

"We stand ready to provide military options if they're appropriate as the president determined."

Kremlin says won’t take part in Trump’s ‘Twitter diplomacy’

The Kremlin said on Wednesday it would not take part in "Twitter diplomacy", after US President Donald Trump tweeted that "missiles will be coming" to Syria.

"We do not take part in Twitter-diplomacy. We support serious approaches. As ever, we believe it is important not to take steps that could damage an already fragile situation," presidential spokesman Dmitry Peskov said in comments reported by news agencies.

Trump tweeted that strikes could be expected in retaliation for an alleged chemical weapons attack on civilians in Syria’s Douma, telling regime-backer Russia to "get ready".

The message comes one day after Russia vetoed a US-drafted resolution at the UN Security Council to set up a panel to identify the perpetrators of Saturdays’ alleged toxic gas attacks.

Russia has said its military specialists found no evidence of a chemical attack, and suggested that rebels staged or spread rumors of an attack to pin the blame on Damascus.